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Discuss Vaillant Turbomax Plus 828E leak at Main Heat Exchanger connection in the Central Heating Forum area at

  1. stephens

    stephens New Member

    The copper pipe that connects is on the LHS (view from front) and I get a small leak every other day. Do not have to top up frequently, just wipe away.
    Also has developed an occasional S.54 fault "delay mode due to flow temperature gradient too steep" which means the hot water runs cold with no amber light (just green flashing) till turn boiler off and on again, then it is OK.
    This happens less frequently if Hot water temp dial is turned down to 12 o clock or less.

    Engineer advises either fixed price repair from Vaillant (£300 approx.) or fit new boiler in the Summertime.
    Was serviced and new Diverter Valve fitted November, has been good until now but is 2002 model so I have had my monies worth.

    Would be grateful for any views on which way to proceed?
    Worried if Vaillant cannot fix but make leak worse as would like time to choose an installer.
    New boiler would be fitted to existing radiators with 10mm microbore.
    Not sure if Vaillant would honour warranty if Heat Exchanger gets blocked when fitted to older system, so was considering Worcester Bosch who seem to be good with warranty claims, if it's still the case?

    Many thanks for any replies. Away tomorrow but will thank any replies Monday.

    Kind regards.
  2. richard978

    richard978 Active Member

    I’d keep repairing seems like a good price and a new boiler will be upwards of 1600 fitted.

    Micro Bore can cause problems on older systems but lots of modern homes have micro bore with no issues at all.
  3. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    System won’t block if cleaned properly or repiped
  4. Mastermixlee

    Mastermixlee GSR

    The fixed repair from vaillant would only cover your leak as far as I'm aware and the s.54 code would continue.

    If the pump is OK then I suspect there's restrictions in your boiler/system causing the spike in temperature rise. Which if left will get worse. So if you keep the current boiler then an investigation into that would be advised and potentially a flush through to clean all the system anyway (which would be required as part of a boiler installation anyway).

    Id get some Independant quotes for the heat exchanger repair (should be simple by description though sometimes time consuming) and a flush through and compare to quotes for a new boiler.

    If you are making do for now then best to get all available information and make an informed decision based on your own financial circumstances.

    Obviously with a new boiler (provided installed correctly by a GSR and registered etc and you get it serviced annually) you'd have a warranty period which varies dependant on manufacturer so weigh that into your choice.

    Hope this has helped.
  5. stephens

    stephens New Member

    Thanks for the replies. I had found this old thread that indicated that a "packing ring" would fix the leak:-

    Vaillant Turbomax Main Heat Exchanger Leaking at Connection

    However the Engineer does a lot of Vaillant repairs and said that you have to replace the main Heat Ex. He said that the female joint on the Hex has build up on it and does not seal well if just the pipe is replaced, hence suggesting trying the fixed price repair.
    He did think though replacement best due to age and the additional s.54 fault.

    Just hoping the leak stays slow so I have more time.
    Vaillant may be able to do the repair, don't think they charge if cannot. However if they try and make the leak worse it's not ideal for trying to get quotes for a replacement boiler. Would rather more time and a slow leak.
    Kind regards
  6. Riley

    Riley S. Mod Trusted Plumber GSR Top Contributor!!

    Why not quotes now and tell people you are looking for later this year??
  7. EvilDrPorkChop

    EvilDrPorkChop GSR

    If it's leaking on the pipe into the heat exchanger then it's usually just the O ring. Done loads, however it's important your GSR engineer gets the proper grey Vaillant O rings as others never seem to work from experience. So that's a simple repair.

    If you're getting S.54 on Hot Water only, and it's intermittent then it's the pump. Even if all your rads get hot, it's the pump. I've had exactly the same issue on the TurboMax Plus 835 version and took a bit of head scratching but it was the pump in the end. Problem was it would only do it once or maybe twice a day then work fine when I was there!

    If it happens more often (Like everytime you run HW), then boiler fires up and the temperature reaches 80oc+ quick then cuts out it's possibly a blocked Plate HEX. Again this can be easily replaced.

    They're cracking boilers, if you can get it repaired i'd be keeping it. It'll probably outlast some of the newer ones :p
    Last edited: Mar 22, 2019
  8. Mastermixlee

    Mastermixlee GSR

    I'd get the engineer to remove the pump and check the impellor for sludge, also get them to check the capacitor on the pump for correct capacitance too. Most of the pumps out there tend to have a 2uf rated capacitor which if out of spec can cause issues with pump speed/starting.

    Without seeing quality of water first hand its difficult to determine best route for you.

    Ive changed the O-rings as @EvilDrPorkChop@EvilDrPorkChop has said above and had no issues. As long as correct O-rings are used and inside is cleaned properly with a little silicone grease on the new seal then they normally seal OK.

    If left leaking however then you'll be risking other components, safety hazards with electrics, and introducing more minerals and deposits into your system by having to refill the system regularly (on a system which is already sensitive to water quality due to the small bore pipework).

    I'd get quotes for the boiler now and then choose course of action as soon as you can.
  9. richard978

    richard978 Active Member

    I rate valiant more than Worcester .They are very expensive to buy so repair if you can.

    I've installed Baxi models that are costing money after 7 years so I think you are doing ok.

    If you have a new boiler avoid Ideal because they are sods for voiding warrantues
  10. stephens

    stephens New Member

    Thanks again for all the replies, very much appreciated.
    Will probably try the Vaillant fixed price repair, they do one with 6 months cover for around £300.

    If it's just an 'O' ring for the leak and perhaps a pump replacement for the s.54, hot water problem could have a good boiler for a few more years. If they cannot repair I don't think they charge.

    £2.5k+ for a new one (ecoTEC Plus or WB CDi classic) would n't be too bad if they lasted like old boilers, but if the new ones are not lasting much longer than 10 yrs it would seem a bit too often to be spending that sort of money.

    Kind regards
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